426 Report of the Department of Entomology of the 



from the first brood of nymphs. In the spring 01 1905 7 Mr. Fred 

 Johnson of the U. S. Bureau of Entomology was led to believe that 

 the spring application of the lime-sulphur wash was quite effective 

 in destroying the eggs of this insect in Niagara county. On the 

 basis of his observations of pear orchards in the Hudson River 

 Valley, Dr. E. P. Felt, 8 in 1910, expressed a similar opinion. 



In describing conditions in Connecticut during 1904 Dr. W. E. 

 Britton 9 stated " after spraying pear trees with lime and sulphur 

 mixtures to kill the San Jose scale it was noted that the pear psylla 

 was scarce, though the insect was observed in other localities where 

 it caused more or less injury." 



In England, Theobald, 10 while working with a closely related 

 species on apple, doubted the value of most washes in killing psylla 

 eggs, and, while apparently he had not tested the lime-sulphur 

 preparations, he recommends the use of a lime-salt mixture for the 

 prevention of the hatching of the eggs. The application is said to 

 act largely as a mechanical barrier to the escape of large numbers 

 of the young, although he suggests that the salt has some osmotic 

 power " as when the quantity of the salt is increased the action 

 becomes greater." 



The experiences of some of the leading growers in New York have 

 borne out the promises of the early experiments with the lime- 

 sulphur wash, and the use of this spray in later years seems to have 

 afforded them almost complete protection against the psylla. On 

 the other hand the results in most plantings have been variable 

 and quite contradictory; and in spite of annual sprayings with 

 lime-sulphur wash before the appearance of foliage the pest has, 

 for several seasons, made serious inroads in pear orchards generally. 

 The true explanation for these differences has been wanting, but 

 the discrepancies appear to have been largely due to habits of the 

 hibernating " flies " as affected by seasonal conditions. 



Very little was known of the over-wintering adults or the circum- 

 stances of oviposition which would appear to be essential for intelli- 

 gent action. To these points the Station has devoted much attention 

 for the purpose of determining the best conditions for effective 

 spraying against the adults and the eggs deposited by them. 



'U. S. Dept. Agr. Yearbook, 1906 (1907). p. 446. 

 •N. Y. State Mus. Bui. 147:45. 1910 (1911). 

 » Conn. State Entomologist. Rpt. 4:213. 1904. 

 '"Insect pests of Fruit, pp. 160-162. 1909. 



